Allantoin (glyoxyl diureide) and derivatives thereof such as ALPANTHA (Schuylkill Chemical Co., Philadelphia, Pa. trademark for "Allantoin DL-Panthenol Modified") are known for their soothing, skin softening and healing activity and have been used in 0.2% concentrations in creams, lotions, lipsticks, hair products (anti-dandruff), cosmetic gels (for their anti-irritant properties), cleansers (removal of scaly and calloused tissue), and moisturizers (increase water-binding capacity of the tissues).
Until now, notwithstanding the acknowledged therapeutic qualities of allantoin and its derivatives including allantoin dl-panthenol modified, the amount of allantoin or allantoin equivalent contained in these materials and employed in hydroalcoholic solutions (also referred to as aqueous-alcoholic solutions), such as after-shave lotions and colognes, has been severely restricted to relatively small amounts of 0.2% by weight or less. It has been found that when amounts of allantoin or allantoin dl-panthenol (modified) of greater than 0.25% by weight (based on the amount of allantoin) are employed in such hydroalcoholic solutions, the allantoin tends to crystallize out of solution within a relatively short period of time.
Accordingly, a long felt want exists in the market place for a stable form of allantoin which may be used in solution in amounts greater than 0.25% (based on the weight of allantoin) and upwards of 0.5% and more without crystallizing out of solution.